After upgrading from 4.19.72 to 4.19.82, my VMs are stuck in a reboot-loop. The boot up to Grub is fine, but when I select an item in the boot menu, the guest reboots after a short while. I can't see any output. I don't see anything unusual in the logs but I'll attach the log from libvirt and dmesg. After I switch back to .72, the guests boots fine. The same issue manifests when booting from "CD-ROM".
The .82-kernel is compiled with sys-devel/gcc-9.2.0-r2, the old was compiled with 8.3. The only change in the kernel config is CONFIG_GCC_VERSION.
I tried to reproduce the issue and found a possible clue: The affected machines both have an Intel Core 2 DUO CPU (T7300 and P8700). The machine that is not affected has an AMD CPU (A10-9700).
Created attachment 595666 [details]
libvirt log of guest
Created attachment 595668 [details]
I recompiled the kernel with sys-devel/gcc-8.3.0-r1 to be sure it's not that; the issue persists.
Same issue after upgrading from linux-4.14.143-gentoo to linux-4.14.152-gentoo on the VM host. After reboot host works fine, but guests with linux-4.14.143-gentoo are stuck in a bootloop.
All kernels compiled with sys-devel/gcc-8.3.0-r1
Are you able to do a git bisect between the last working kernel and the first on working kernel?
Yes, I'll get right to work. :-)
496cf984a60edb5534118a596613cc9971e406e8 is the first bad commit (commit 16cfacc8085782dab8e365979356ce1ca87fd6cc upstream).
Upstream patch: bf03d4f9334728bf7c8ffc7de787df48abd6340e
Will be in next stable kernels.
I can confirm the fix works with 4.19.82.